Caxton

• Fix versions for built-in resource packs
  • This only affected the 1.20.3 version, so this update is only applicable to this version.

• Add Forge versions
  • NeoForge versions are coming later; waiting for MixinExtras remapping support on Architectury
• Integrate with ImmediatelyFast if present
• Detect when the native library needs to be written to the instance folder rather than doing so on every launch
• Add /caxtonshape and /caxtontext commands
• Migrate to core shader APIs provided by Fabric and Forge
  • Fabric API 0.77.0 or later is now required for Minecraft 1.19.2 or earlier
• Fix a lot of bugs and crashes

Port to 1.20.3-rc1.